Biology 625
ANIMAL PARASITOLOGY
Fall semester lecture note outline

Updated: 24 September 1999

1. The most widely accepted classification divides the digenea into 2 superorders (1957, Exp. Parasitol. 6: 306-349)
   1. SUPERORDER: Anepitheliocystidia [embryonic, non-epithelial excretory bladder retained in adults; no oral stylet]
      1. Order: Strigeiformes
      2. Order: Echinostomatiformes (1 superfamily)
      3. Order: Paramphistomiformes (2 superfamilies) (often included within Order: Echinostomatiformes)
      4. Other miscellaneous orders, which are often included as superfamilies in the Order: Strigeiformes
   2. SUPERORDER: Epitheliocystidia [embryonic excretory bladder replaced by new epithelial lining derived from mesoderm; oral stylet common]
      1. Order: Plagiorchiformes (2 superfamilies)
      2. Order: Opisthorchiformes (3 superfamilies)
2. However, newer ultrastructural studies suggests that this system has serious flaws (1987, Parasitology, 95: 429-460). Thus, the 10 major orders will be presented without superorder subdivision.

Orders to be learned in class

1. Order: Strigeiformes
   1. cercariae with two eyespots
   2. acetabulum in adult midventral
   3. cercariae encyst in second intermediate host
   4. two pairs flame cells in miricidium (other groups one)
   5. adult body with spines
   6. ovary between testes
   7. genital pore midhindventral
   8. uterus extending anteriorly from ovary to near acetabulum, then posteriorly to genital pore
   9. includes Clinostomidae, Sanguinocolidae, Spirorchidae, Bucephalidae, Neodiplostomatidae, Schistosomatidae, Strigeidae

2. Order: Echinostomatiformes
   1. no eyespots in cercariae
   2. cercariae encyst externally on some object
   3. ventral sucker of cercariae midventral
   4. acetabulum in adult midventral
   5. adult body with spines
   6. redia with appendages and collars
   7. uterus extending from ovary to preacetabular region
   8. most distomes
   9. includes Fasciolidae, Echinostomatidae

3. Order: Paramphistomiformes
   1. most classifications place this in Echinostomatiformes
   2. cercariae with two eyespots
   3. cercariae encyst externally on some object
   4. pharynx at junction of esophagus and cecal bifurcation
   5. redia with appendages
   6. includes Paramphistomatidae (entirely amphistomes), Notocotylidae (all monostomes, although some monostomes in other groups)

4. Order: Plagiorchiformes
   1. acetabulum in adult mid-ventral
   2. adult body with spines
   3. rediae without appendages
   4. cercariae encyst in second intermediate host
   5. cercarial tail not furcate
   6. seminal receptacle present
   7. dorsoventral fold on cercarial tail present
   8. eggs very small, usually less than 40 micrometers
   9. xiphidocercariae (cercariae with stylet)
   10. includes Allocreadidae, Troglotrematidae, Prosthogonimidae, Plagiorchiidae, Dicrocoeliidae, Haematoloechidae

5. Order: Opisthorchiformes
   1. cercariae with two eyespots
   2. acetabulum in adult body midventral
   3. adult body with spines
   4. rediae without appendages
   5. cercariae encyst in second intermediate host
   6. cercarial tail not furcate
   7. seminal receptacle present
   8. primary finfold present on cercarial tail
   9. eggs very small, usually less than 40 micrometers
   10. eggs hatch in molluscan host after ingestion
   11. no cirrus
   12. includes Opisthorchiidae, Heterophyidae

Orders NOT to be learned in class:

1. Order: Heronimiformes
   1. symmetrically branched sporocysts
   2. eggs hatch in utero
   3. ventral sucker degenerates in adults
   4. single family Heronimidae

2. Order: Haploporiformes
   1. cercariae with two eyespots
   2. cercariae encyst externally on some object
   3. acetabulum of cercariae and adult midventral
   4. adult body with spines
   5. rediae without appendages
   6. uterus extending from ovary anteriorly to halfway between bifurcation and pharynx
   7. includes Haploporidae

3. Order: Transversotrematiformes
   1. cercariae with two eyespots
   2. furcocercous cercariae
   3. body transversely elongated
   4. rediae with appendages
   5. single family Transversotrematidae

4. Order: Hemiuriformes
   1. cercariae with two eyespots
   2. acetabulum in cercariae and adults midventral
   3. adult body with spines
   4. rediae without appendages
   5. furcocercous cercariae
   6. includes Hemiuridae, Syncoeliidae

5. Order: Lepocreadiiformes
   1. cercariae with two eyespots
   2. acetabulum in adult midventral
   3. adult body with spines
   4. rediae without appendages
   5. cercariae encyst in second intermediate host
   6. cercarial tail not furcate
   7. seminal receptacle present
   8. dorsoventral fold on cercarial tail
   9. eggs very small, usually less than 40 micrometers
   10. eggs hatch in molluscan host after ingestion
   11. includes Lepocreadiidae